This invention relates generally to communication networks and, more particularly, to a system and method of using Local Number Portability (LNP) features to redirect terminating calls to a service node, such as a Service Control Point (SCP), so that the network services to communication devices can be initiated, monitored, and billed.
In an ISDN User Part (ISUP) quasi-associated signaling system, where ISDN stands for Integrated Services Digital Network, a landline telephone is typically serviced through a switch, or a Service Switching Point (SSP). Both the telephone and the SSP have fixed locations inside a district with an area code. Each SSP is associated with an exchange number, and the SSP maintains a database of the telephones it services. In a ten digit telephone number (x1x2x3-x4x5x6-x7x8x9x10), the area code is the first set of three digits (x1x2x3), the exchange number is the second set of three digits (x4x5x6), and the subscriber number is the last set of four digits (x7x8x9x10). The local number of a subscriber is the exchange and subscriber numbers (x4-x10).
Telephone users are familiar with the inconvenience of acquiring a new telephone number after a change of residence. However, it is very important to most businesses that they retain their old local telephone numbers when changing business addresses or locations. Further, to encourage competition between telephone service providers, non-business users must be permitted to change service providers without losing their preexisting local telephone numbers. To this end, Local Number Portability (LNP) procedures have been developed.
FIG. 1 is a schematic block diagram illustrating the concept of LNP in a communications network 10 (prior art). LNP permits a local telephone number to be moved from a first (original) exchange to a second (new) exchange, or moved from a first switch (SSP) to a second switch (SSP). That is, LNP processes permit the telephone number to become associated with the new exchange, despite the fact that the telephone number is from the old exchange. Telephone 12 is shown as formerly associated with switch 14, but presently associated with switch 16. The previous association with switch 14 is indicated with dotted line 18. Originating telephone 20 originates a telephone call to terminating telephone 12. Local exchange (N-1) switch 22 maintains a record that at least one number associated with switch 14 is a ported local telephone number, or a number that has moved to a new exchange. Therefore, all numbers in that exchange (associated with switch 14) must be checked for LNP. Out-of-band communications are established between switch 22, through Signal Transfer Point (STP) 24 to a LNP database 26. LNP database 26 maintains a record of ported numbers. A Local Routing Number (LRN) is returned to switch 22 which permits switch 22 and switch 16 to establish a trunk connection for voice communications between telephones 20 and 12.
FIG. 2 is a schematic block diagram of a prior art communication network 10 where special services are being provided. Specifically, FIG. 2 depicts the rerouting of voice communications and Signaling System 7 (SS7) signals. Initially, a call from originating telephone 40 is attempting to terminate to a mobile subscriber terminating telephone 42. The call arrives at the last switch outside of a mobile subscriber's home switch, (N-1) switch 44, without a check having been performed to determine if the number has been ported to another exchange or carrier. In the second step, of checking the LNP database 46, the Mobile Directory Number (MDN) is determined not to need redirection (i.e., the number has not been ported).
In step 3 the call is delivered to the home MSC 48. In step 4 the call is delivered to a service node 50 for special feature handling. Examples of special features include prepaid service platforms, where a customer has a prepaid account that is debited as the call progresses, and call attendant services which require caller input, such as automated recordings that redirect calls for services in response to voice or dialing prompts from the telephone user.
In step 5 the call is returned to the MSC 48 for routing to the final destination, terminating telephone 42. In step 6 the call is completed, delivered to the terminating telephone 42 or routed to another destination. As depicted, switch 48 is a Mobile Switching Center (MSC) and terminating telephone 42 is a wireless telephone. However, the same principles apply when switch 48 is a Class-5 landline switch (SSP) and terminating wireless telephone 42 is a landline telephone. Generally, MSC and Class-5 switches are referred to herein as a terminating switch to cover both wireless and landline applications.
FIG. 3 is a schematic block diagram of a prior art communication network 10 requiring a loop-around circuit for voice communications. Initially, a call is attempting to terminate with mobile subscriber terminating telephone 42. The call arrives at the last switch outside the MSC 48, namely (N-1) switch 44, without a check having been performed to determine if the terminating telephone 42 has a telephone number that has been ported to another carrier, or if the number is associated with a new exchange. In step 2 the MDN is determined not to need redirection after a check with LNP database 46. That is, the number has not been ported and has not been converted to an LRN.
In step 3 the call is delivered to MSC 48. In step 4 the call is forwarded using ISUP trunks to an SCP 52 for special feature handling. The SCP 52 is now a network element controlling the call using ISUP signaling. Node 52 can perform special handling using ISUP. For example, a call can be recalled to the SCP 52 for diversion to another destination or call release. Examples of these procedures include prepaid services and call attendant redirection services, including time-of-day redirection schedules. The physical voice path is a loop-around circuit 54 on the MSC 48. Only the ISUP (out-of-band) signaling is routed to SCP 52. Switch 52 must be inserted to monitor the out-of-band control signal communications. For example, the length of the call must be monitored and compared to the prepaid account. Therefore, the control signals indicating the start and finish of the voice communication are monitored. The SCP 52 checks the out-of-band messages to determine whether terminating telephone 42 is allowed to receive this call (i.e., has enough money). All progress messages, such as Setup and Teardown messages, associated with this call are communicated through SCP 52.
In step 5 the call is forwarded to the MSC 48 for routing to the final destination. From the perspective of the MSC 48, the incoming initial address message (IAM) appears to be a new incoming call requiring call completion. The called number of the IAM originating from the SCP 52 may or may not be modified depending on the feature requirements. In step 6 the call is completed, delivered to terminating telephone 42, or routed to another destination.
Using the procedures described in FIGS. 2 and 3, a dedicated telephone number range can be used to alert a switch of a subscriber requiring special services—for example, a dedicated 10,000 number block, such as all the telephone numbers in the range between 206-419-0000 and 206-419-9999 can be set aside. Such a 10K number block can be used to alert the system switches that a telephone number requires prepaid subscriber services. However, such a service would require the subscriber to change telephone numbers to receive such special services. Therefore, using 10K number blocks to provide notification to the system of subscribers requiring special services creates a corresponding inconvenience to the subscribers. In fact, many subscribers are unwilling to change telephone numbers in exchange for a telephone number with enhanced capacities. Further, the use of loop-arounds in the system to monitor the special services requires additional system resources and additional system process steps.
It would be advantageous if so-called “t1” circuit cards, specifically dedicated to provide special services which engage loop-around features in a system switch, could be eliminated. Further, it would be advantageous if specially dedicated t1 circuit cards could be replaced with conventional t1 circuit cards to expand the ability of the system to process conventional telephone calls.
It would be advantageous if a telephone subscriber could receive additional services from the network without having to change their telephone number.
It would be advantageous if an LNP database could be used to identify customers who are receiving special services from the network.
It would be advantageous if the LRN, provided from a LNP database, could be used to route calls to special service nodes when calls are made to customers receiving these special services.